GAITHERSBURG, Md., April 3, 2008 /PRNewswire-FirstCall/ -- Iomai Corporation today announced that it has signed an agreement with Merck & Co., Inc. to conduct proof-of-principle preclinical studies evaluating the use of the Iomai needle-free immunostimulant patch.

Merck has first option to negotiate an exclusive license. These preclinical proof-of-principle studies will be conducted using an undisclosed Merck vaccine. Iomai recently announced results of a 500-person Phase 1/2 trial in which a clinically relevant adjuvant effect was observed when a version of the immunostimulant patch was administered in combination with an injected vaccine for pandemic influenza, and data from a prior European trial demonstrated the ability of the immunostimulant patch to boost the immune response of the elderly who receive an injected seasonal influenza vaccine.

"This agreement with Merck allows us to further evaluate the possible applications of our patch," said Stanley C. Erck, president and chief executive officer of Iomai. "Our immunostimulant patch has the potential to improve the immune response to a wide variety of vaccines, allowing for more effective vaccines, or vaccines that work at a lower dose."

The Iomai approach uses a potent adjuvant, applied to the skin through a patch that is affixed over the site of the injected vaccine. Once the patch is applied, the adjuvant passes into the skin, targeting cells called Langerhans cells. Those specialized skin cells carry the adjuvant into the lymph nodes, where it works to boost an individual's immune response to the vaccine. This proprietary approach is known as transcutaneous immunization (TCI).

Last year, the Department of Health and Human Services (DHHS) awarded Iomai a $128 million contract to fund the company's development of a dose-sparing patch for use with a pandemic influenza vaccine, and that contract is currently funding the Phase 1/2 pandemic influenza trial. The patch being used in that program is similar to the one that will be used in the Merck collaboration, with the same adjuvant and delivery system.

ABOUT IOMAI CORPORATION

Iomai Corporation discovers and develops vaccines and immune system stimulants, delivered via a novel, needle-free technology called transcutaneous immunization (TCI). TCI, discovered by researchers at the Walter Reed Army Institute of Research, taps into the unique benefits of a major group of antigen-presenting cells found in the outer layers of the skin (Langerhans cells) to generate an enhanced immune response. Iomai is leveraging TCI to enhance the efficacy of existing vaccines, develop new vaccines that are viable only through transcutaneous administration and expand the global vaccine market. Iomai currently has four product candidates in development: three targeting influenza and pandemic flu and one to prevent travelers' diarrhea. For more information on Iomai, please visit http://www.iomai.com.

Some matters discussed in this press release constitute "forward-looking statements" that involve known and unknown risks and uncertainties that could cause actual results to differ materially from those expressed or implied by the forward-looking statements. Such forward-looking statements include statements about the ability of the immunostimulant patch to improve the immune response to vaccines, including by making them more effective or by lowering the effective dose, and the possibility of further collaboration with Merck beyond the initial preclinical studies described in this release. Applicable risks and uncertainties include, among others, that future preclinical and clinical trials may not replicate results seen in previous clinical trials; that pre-clinical studies described in this press release may fail to indicate that the immunostimulant patch improves the immune response or reduces the necessary vaccine dosage by as much as anticipated; that the timing and effectiveness of the pre-clinical are dependent on sufficient coordination and cooperation with Merck and third parties; that potential collaborators, including Merck, may determine to wait for additional preclinical and/or clinical data prior to entering into a collaboration or may be unwilling to collaborate on terms Iomai deems acceptable; that Iomai may be unable to obtain the regulatory approvals necessary to conduct additional clinical trials or to market any product candidates using the Iomai's immunostimulant patch; that development costs may exceed expectations; that Iomai may fail to adequately protect its intellectual property or may be determined to infringe on the intellectual property of others; and the other risks identified under the heading "Risk Factors" in Iomai's annual report on Form 10-K for the year ended December 31, 2007 and filed with the Securities and Exchange Commission. Iomai cautions investors and others not to place undue reliance on the forward-looking statements contained in this press release. You are encouraged to read the Company's filings for a discussion of these and other risks and uncertainties which are filed with the Securities and Exchange Commission and available at www.sec.gov. All statements in this press release only speak as of its date, and Iomai undertakes no obligation to update or revise the statements.